【JST-052】One-on-one consultation office for coal, natural gas, and biomass indirect liquefaction technologies

Regarding the liquefaction of oxygen-containing coalbed methane, is pre-deoxidation better, or is low-temperature distillation in a cryogenic column better? The existing coalbed methane contains 1% oxygen; H2S cannot be detected, but there is an odor at the wellhead, suggesting the presence of H2S. Furthermore, which company has carried out such an example, and what methods were used? Thank you

This post was last edited by fossil-zhang on 2012-3-29 23:11. First, it is necessary to determine the specific composition of coalbed methane. If Fischer-Tropsch synthesis is considered for the liquefaction of coalbed methane, high requirements are placed on the gas composition, such as the hydrogen-to-carbon ratio, oxygen content, and sulfur content; the requirements for syngas used in coal liquefaction can serve as a reference. The 1% oxygen must be removed, and the sulfur level must be below 5 ppb. Just because you can’t detect sulfur doesn’t mean there is no sulfur present; low concentrations are indeed difficult to detect, and specialized sulfur detectors are required. Such detectors are available in China, at a cost of around tens of thousands of yuan. So first, it is necessary to analyze coalbed methane and address specific issues; as long as the exact composition is known, there are specific methods to deal with them, such as deoxygenation, desulfurization and purification, conversion, reforming, decarboxylation, and so on.

What are the methods for removing oxygen and nitrogen from natural gas? What is the energy consumption?

You can take a look at this post, which discusses the main equipment used for the decarburization, deoxygenation, dehydration, and denitration of natural gas: http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=205724. As for the methods and energy consumption, here is some text that may be useful as a reference: 1) Pressure swing adsorption – This method involves carrying out adsorption operations under high pressure, and then reducing the pressure to cause the adsorbent to release the trapped substances; part of the product gas is used as the washing gas for desorption. The adsorption process is carried out under pressure, while the regeneration flushing is generally performed at atmospheric pressure. Pressure swing adsorption has advantages such as low energy consumption, short desorption time, and easy operation. However, its product recovery rate is relatively low, at only 40%–50%. This is because there are voids in the adsorption layer, and the product gas stored in these voids is released and lost during the desorption phase. Additionally, a portion of the product gas must be used for flushing purposes. There is a conflict between product purity and recovery rate; increasing the recovery rate leads to a decrease in purity. Therefore, using this method is not cost-effective. 2) Membrane separation: The membrane separation method has many advantages; it does not require a change in phase, the equipment is simple, it requires little space, and it can operate continuously. However, the permeability of various gas components through the film varies; the amount of penetration is related to the permeation coefficient of each component, to the area of the permeable membrane, and also to the partial pressure difference of the gas components on either side of the membrane. Product gas is lost during separation, and excessive pressure poses safety risks to the mixture. 3) Combustion deoxidation method: Compared with the first two methods, the combustion approach achieves more thorough deoxidation, enabling the oxygen content to be reduced to below 0.5%. The downside is that the equipment is relatively complex, and it also increases the levels of CO2, CO, SO2, and H2S in the feed gas during the combustion process. Natural gas usually contains little CO2; some types contain no sulfur compounds at all. Molecular sieves can be used to remove CO2 while dehydrating the gas. If combustion-based deoxidation is used, after deoxidation, an additional set of complex alkanolamine acid-removal equipment for removing CO2 and sulfides is required, which not only increases capital investment and energy consumption but also makes operation more inconvenient. 4) Cryogenic separation method: The principle of the cryogenic separation method is to first condense a gas mixture into a liquid, and then separate its components based on their respective evaporation temperatures. This is a relatively suitable method for separating mixed gases. Firstly, this scheme yields products with the highest purity ； Secondly, this approach is relatively safe; the separation process takes place at low pressure and low temperature, so combustion and explosion are unlikely to occur even when in the range where methane can ignite and explode ； Third, this approach is the most cost-effective, as producing liquefied natural gas (LNG) requires reducing the temperature of the feed gas to the methane liquefaction temperature. During this cooling process, low-temperature separation can be carried out to simultaneously separate and remove oxygen and nitrogen, without the need for additional energy consumption for their removal. Other methods either require increased energy consumption or result in the loss of some of the feed gas; some also increase the level of acidic gases, raising the costs associated with gas purification. Moreover, they can only remove oxygen and not nitrogen simultaneously. The cryogenic separation method can simultaneously separate and remove oxygen and nitrogen. Actually, I don’t know much about this area. If you want to get more specific and detailed information, I suggest you post a question in the Petrochemicals, Natural Gas, and Chemicals forum.

Could the original poster provide an overview of the current status of the industrialization of MTO, MTG, and MTP technologies in China, as well as share their views and opinions?

This post was last edited by fossil-zhang on 2012-3-30 at 14:53. I work in Fischer-Tropsch synthesis; I’m not involved in MTO/MTG/MTP. There are many discussions and introductions related to these technologies in the coal-to-oil and olefins forums, and they are much more professional than what I can provide – you should take a look there. Overall, based on the current situation, MTO/MTP technology has been industrialized in China, and it is the only place in the world where such technology has been put into industrial use, which is certainly worth acknowledging. As for MTG, there are some projects operating in China, but it seems they have not yet reached the stage of industrialization. Nevertheless, there are still many problems with such technologies. Firstly, regarding the technology itself, although China has managed to develop MTO independently and its level is among the highest in the world, looking at the MTO projects that have already been put into operation, China has not yet mastered the related technologies in the upstream and downstream stages well. Technologies such as gasification, methanol synthesis, olefin separation, and olefin polymerization are all of foreign origin; only MTO itself is developed by Chinese companies. Even though the technologies involved in the upstream and downstream processes are relatively mature, it is worth reflecting on why China’s own technologies are not yet able to be used in such large-scale projects. As for MTP, needless to say, both of the MTP projects in operation use foreign technology. Although many organizations and research institutes are also developing related technologies, they are still a long way from industrialization. Therefore, regarding methanol-to-olefins (MTO/MTP) itself, it cannot be assumed that industrialization has been successful just because there are many large-scale projects currently in operation or under construction. Not to mention the fact that there is still room for improvement in terms of the technology itself, nor can we ignore the inherent problems associated with methanol-to-olefins production, such as water consumption, energy consumption, pollution, carbon emissions, and economic viability. Can we pay more attention to the industries related to methanol-to-olefins technology? This isn’t merely a matter of reducing costs, improving economic efficiency, and increasing the rate of domestic production; it’s about driving the overall improvement and progress of a whole host of related industries. As for MTG, its industrial production was established in New Zealand by EXXON-MOBIL back in the 1980s and 1990s; however, due to the subsequent decline in oil prices, that MTG plant in New Zealand was converted to produce methanol. In China, due to the popularity of coal chemical industry itself, other projects have been restricted; MTG has attracted a lot of attention. There are also several small-scale pilot or demonstration projects in operation in China, with the technology coming from EXXON-MOBIL abroad and the Shanxi Coal Chemical Research Institute in China. I believe this technology has clear advantages: it converts methanol into gasoline, and the quality of the resulting gasoline is excellent. The process pathway has been proven effective (in fact, its principle is similar to that of MTO/MTP, with only slight differences in the catalysts and reactors used). It can help address the shortage of liquid fuels in the country. There is still plenty of room for development; it depends on the performance of the existing devices at present.

I have two questions for the moderators: 1/ There is currently quite a lot of research on FT synthesis catalysts in China. I would like to know to what extent the performance of these FT catalysts used by various research institutions affects the profitability of coal-to-oil plants My humble opinion: if an iron-based catalyst is used for the FT catalyst, its price is likely not to be too high. Your catalyst can produce 10 tons of oil per ton, while mine can produce 8 tons per ton; this shouldn’t have a significant impact on the overall efficiency of the plant, right? 2/ Indirect biomass liquefaction is also being carried out by some companies in China at present, but due to limitations in the availability of raw materials, the scale cannot be very large. If it is designed according to the current processes used in coal-to-oil plants, it may be functional enough, but no scale advantages can be achieved. I’m curious to know what the moderator thinks about this issue. .

This post was last edited by fossil-zhang on 2012-4-1 at 17:36. 1) There are indeed many institutions in China—including companies, research institutes, and universities—that have conducted or are still conducting research on Fischer-Tropsch synthesis catalysts. However, as far as I know, most of these efforts are of a minor nature, aimed at publishing articles; only a few have carried out systematic research over many years with the goal of achieving industrial application. Among these, I believe no more than three have actually reached an industrial scale (including pilot-scale production). Basically, these institutions work with both iron and cobalt catalysts, though with different focuses—some may be more proficient in using iron catalysts, others in cobalt catalysts, while still others are skilled in using both. Units of this scale all have fairly good technology, and the performance of their catalysts varies; however, there aren’t very large differences in the quality of these catalysts. Furthermore, it is necessary to establish a concept first: in synthetic oil technology, catalysts are one of the important influencing factors, but by no means the only ones. A good catalyst will not be effective in a poorly designed process setup, while a well-designed process setup can compensate for the shortcomings of an ordinary catalyst. Of course, we hope that a good process design, combined with a high-performing catalyst, can enhance economic efficiency. Once again, as I’ve said before, it cannot be assumed that iron catalysts are much cheaper than cobalt catalysts. For catalysts used in industrial applications, when taking into account everything from raw materials to manufacturing and final use, the cost of iron catalysts is actually not much lower than that of cobalt catalysts. You can check out my previous posts on this topic; therefore, this notion needs to be changed. Iron catalysts and cobalt catalysts are not really comparable; under the same reaction conditions, there are significant differences in their activity, product selectivity, and lifespan. The methods used for manufacturing these catalysts differ, as do the processes employed, as well as the hydrogen-to-carbon ratio of the syngas that is suitable for use. The reaction conditions appropriate for each catalyst also vary, and the methods for activating the catalysts differ as well, leading to differences in the composition of the products produced. How can we compare when the benchmarks are different? Therefore, do not compare the quality of catalysts in isolation; instead, consider the catalyst together with the entire system as a whole to assess whether the fit between them is appropriate and optimal We always say that first, you need to figure out what you want to do What kind of product do you want? Where does the gas source come from? How large is it? Only then can you consider what kinds of processes and catalysts are suitable. You shouldn’t simply use cobalt just because others do, or iron just because others use it, or a slurry bed just because that’s what others opt for. Perhaps a fluidized bed or a fixed bed would be more appropriate for you. What matters here is better matching, and there is no such thing as the most advanced or the best. You say that it makes little difference if one catalyst produces 8 tons of oil while another produces 10 tons? It depends on how you look at it. If we’re talking about the entire lifetime of the catalyst, there is indeed a difference between 8 tons and 10 tons, as the production volume differs; however, other differences in the plant might compensate for this difference. But if it’s the output over a certain period of time (such as a day or a month), then the difference is significant. A catalyst with a long lifespan can be used for a year, while one with a short lifespan can only be used for three months – isn’t that a big difference? Especially when the cost difference between catalysts is not significant and replacing the catalysts is troublesome, this difference is quite large. The lifespan of cobalt catalysts is generally longer than that of iron catalysts. Therefore, the catalyst itself must be considered in a holistic manner—taking into account its cost, activity, selectivity, and lifespan. One cannot consider these aspects in isolation. If someone tells you that their catalyst has high activity or low cost, they’re probably trying to deceive you. 2) Regarding bio-based synthetic oil, there are indeed the issues you mentioned, but what we need to consider first are its starting points and advantages. No technology is perfect without any flaws; just because there are shortcomings does that mean we shouldn’t use it? Who says it has to be on a large scale to succeed? I know that some units have interesting designs, such as skid-mounted or mobile types, which can overcome some of the previous shortcomings. Areas rich in biomass resources are all in rural areas. By constructing plants of appropriate scale within a certain radius based on those resource locations, it is possible to meet part of the local demand for fuel and electricity (by combining biomass power generation with power generation from synthetic oil exhaust gases), as well as to address employment issues for rural workers. Of course, putting this into practice is not as simple as I’ve described; many obstacles and difficulties will arise, including technical and policy-related issues such as biomass gasification, raw material collection, economic viability, and subsidies. But my approach is to start with a good foundation – once that is in place, one should take action to solve problems through practice. If one gives up at the first sign of difficulty due to a lack of practical effort, then nothing will get done. In short, I am still optimistic about biomass-based synthetic oils. Many things in China cannot be handled by relying on past experiences; just because past experiences with coal-based or natural gas-based synthetic oils suggest that small-scale production is not feasible, does that mean that synthetic oil production on a small scale is impossible in all cases? I have specifically discussed this issue in previous posts. The same problem exists with biomass as well; what we need to do is to recognize the advantages, understand the difficulties and shortcomings, and address those difficulties and shortcomings in practice.

Hello! I am involved in the production of maleic anhydride through water absorption using n-butane; currently, our plant is still in the trial operation phase. The driving time each time is never a month; in Xinjiang, it can reach one month. Moreover, the cooling time after cleaning is very short on that side, while it’s relatively long on our side – about a week. I would like to ask what methods can be used to extend the driving time. By driving time, I mean a normal increase in it. I am located in Pinghu, Zhejiang! Thank you!! ! ! ! ! ! ! ! ! ! !

I’m sorry, I’m not familiar with your question and can’t answer it; I suggest you ask in the relevant forum.